Phosphate pads are great for lowering your phosphate levels in your aquarium. Excess phosphates in the water column can cause algae growth and compromise fish health. Adding phosphate absorbing filter pads to your filter can ensure your tank remains healthy. They can easily be be cut down to the size of your filter for a perfect fit. Live plants prefer at least some phosphates be available in the water column, so this filter pad is best used in tanks with elevated phosphate levels.